Field of the Invention
Embodiments of the disclosure generally relate to field of display technology, in particular to an array substrate and a method for manufacturing the same and a display device.
Description of the Related Art
An Organic Electroluminescent Device (OLED) has been widely used in display technique due to its advantages such as self-luminous, fast response, wide viewing angle, high brightness, brilliant color, light-weight and the like with respect to a Liquid Crystal Display (LCD). A method for forming films of the OLED mainly comprises an evaporation process and a solution process. The evaporation process has been widely used in a small-sized OLED and has realized a mass production. A forming film method based on the solution process mainly comprises ink jet printing, nozzle coating, spin coating, screen printing and the like. The ink jet printing technique may realize a mass production of a larger-size OLED due to high material utilization thereof. In the existing method for manufacturing the OLED, it is necessary to pre-form a pixel defining layer (PLD) on an electrode of a substrate so that ink droplets may accurately flow into respective RGB sub-pixel regions.
In an embodiment as shown in FIG. 1 in the prior art, the PDL 4 of the OLED generally has an isosceles trapezoidal shape. Meanwhile, the PLD 4 is often made of a hydrophobic material having a small surface energy in order to ensure that the ink droplets spread in pixels of an electrode layer 3 made of Indium Tin Oxide (ITO) without overflowing to the PDL region outside the pixels. However, a solvent in the ink droplets close to an edge of the PDL will volatilize quickly due to a surface energy difference between the ink droplets and the PDL 4 when contacting with each other and a slope angle of the PDL. Therefore, the ink droplets will be formed as an uneven thin film which is relatively thicker at an edge thereof and is relatively thinner at the middle thereof after being finally dried, i.e. coffee ring effect occurs. Due to this coffee ring effect, in respective film layers in an organic material functional layer 5 of the finally formed display device, a thickness of each film layer close to the PDL will not be uniform. An uneven film layer thickness would occur at a region 51 of the organic material functional layer, so that an uneven brightness will be generated in the display device, which in turn adversely affects display quality of image of the display device.